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With the Flex 2, Fitbit upgrades its original entry-level fitness tracker with a fully waterproof design, color LEDs, automatic activity tracking, and a variety of ways to wear it.

29 Sep 2016Timothy Torres

The Flex 2 ($99.95) is Fitbit's first fully waterproof fitness tracker, as well as its slimmest. It automatically tracks swimming, along with other activities like biking, running, and walking. There's no built-in GPS or heart rate monitoring, but that's no surprise at this price point. Instead of a display, there's a row of colorful lights that blink to indicate your progress and alert you of phone notifications. The Flex 2 is slim and modular, so you can place the tracker portion in a variety of different bands and bangles. It's a great entry-level tracker, though the Misfit Ray puts up a tough fight in the style department.

Design and FeaturesLike Fitbit's Alta and Charge 2, the Flex 2 is essentially a tiny, rectangular module you can swap between various wearable accessories. Smaller than the original Flex, the tracker itself measures just 0.2 by 0.4 by 1.3 inches (HWD) and weighs so little it barely registered on our scale. When placed inside one of the included bands, it weighs 0.3 ounces. At 0.44-inch wide, the band itself is one of the trimmest trackers we've seen since the 0.47-inch Misfit Ray.

The bands, made of silicone, come in Small (for wrists 5.5 to 6.7 inches in circumference) and Large (6.7 to 8.1 inches) sizes. You can choose between black, gray, lavender, magenta, navy, pink, and yellow, and additional bands are available for $14.95 each. There are also bundles—a Pink Pack with pink, lavender, and magenta bands, or a Sport Pack with gray, navy, and yellow bands—for $29.95. A bangle accessory in gold or rose gold is $99.95, while a silver stainless steel version (pictured below) costs $89.95. A pendant accessory in gold is $99.95, and a silver stainless steel variant goes for $79.95.

The included silicone band uses prongs to secure itself around your wrist, which I found a bit difficult to get on. Once fastened, though, it stays on. And like the Ray, it's small enough that it's comfortable to wear all day; I frequently forgot it was even on.

Left to right: A stainless steel bangle accessory, the Flex 2, its charging cradle, and a pink silicone band

Like the original, the Flex 2 uses five small LEDs that act as indicators to show how close you are to achieving your desired goal (such as walking 10,000 steps, the default setting). Each solid light represents a portion of your daily step goal, and you can double-tap the device to see your progress. The lights also indicate when you receive a call or text (as long as your phone is nearby), have set a silent alarm, or trigger an idle alert (more on those shortly). Unlike the original Flex, the LEDs flash different colors and are integrated vertically, rather than horizontally, to accommodate the slimmer design. Vibrations accompany each notification. That's a bit more information at a glance than you get on the Ray, which only has one LED that blinks various colors.

On a full charge, the Flex 2 should last five days, just like Fitbit's other devices. As always, it uses a proprietary charger, which means you'll need to buy a replacement if you lose or break it. And the one from your first Flex won't work. The Ray, meanwhile, is powered by three replaceable coin cell batteries that last up to six months.

The Flex 2 is fully waterproof—a first for Fitbit. It can be used down to 150 feet underwater for several hours, and it automatically tracks swimming stats, including lap counts, pace, and total duration, which is similar to the Misfit Ray. If you want a waterproof fitness tracker with a display, the Polar A360 is a solid option.

Setup, App, and PerformanceTo pair the Flex 2, you need to download the free Fitbit app on your Bluetooth-enabled Android, iOS, or Windows device, create an account (if you don't already have one), and search for the Flex 2. You then have to double-tap the Flex 2 itself to confirm the connection. Including a software update, I paired the tracker with a {{ziffarticleSamsung Galaxy S6 in about ten minutes. Once paired, the Flex 2 automatically syncs with your device whenever it's in range. You can manually sync, too.

Equipped with a three-axis accelerometer, the Flex 2 automatically tracks your active minutes, calories, distance, steps, and sleep. Like the Alta, there is no altimeter, heart rate monitor, or GPS, so the Flex 2 isn't meant for quite the same level of advanced self-quantification as the more expensive Fitbit Surge. But it's accurate in what it does track.

I tested the Flex 2 against both the Charge 2 and the Misfit Ray, and all three trackers delivered comparable results. Each device was never more than two to three hundred steps apart, which is an acceptable level of deviation. Recorded distances were similar, too, though runners will want a tracker with GPS. The Flex 2 also collected seemingly accurate data about my sleeping habits.

As mentioned, the Flex 2 has idle alerts, so when you've been inactive for too long, it vibrates and displays a magenta light to remind you to walk 250 steps before you return to your seat (a number you can adjust in the Fitbit app). It's an effective way to get you out of your seat and moving, but you can adjust when the alerts happen or turn them off entirely.

The Flex 2 also automatically tracks exercises like biking, hiking, running, and soccer. It takes about 15 minutes to recognize an activity, which is something we've seen in other devices with automatic tracking. That means if you go for a short jog, you might be done before the Flex 2 starts tracking it. Due to the lack of a button or screen, there's no way to start or track activities manually. That said, the Flex 2 tracked every jog and walk I did.

The Fitbit app is the same one used with other Fitbit devices, and it's one of our favorite fitness apps. Keep in mind you'll be using it frequently, since the Flex 2 has no display. You can view all of your data in detail when you tap specific stats. If you tap on Sleep, for instance, you'll see a weekly timeline with your average amount of sleep, and the number of times you were awake, asleep, and at rest. There's also an option to edit activities that are automatically recorded in case they're misidentified, a food tab where you can record what you eat, and multiple options for setting silent alarms.

ConclusionsWhen it comes to $99 fitness trackers, it comes down to the Fitbit Flex 2 and the Misfit Ray. They each deliver accurate measurements, notifications from your phone, silent alarms, and they're both waterproof. The Flex 2 has more indicator lights to give you a better idea of your progress, and Fitbit's app has a bigger sense of community. The Misfit Ray wins in the style department, with a sleeker, more minimal design. It also has longer battery life. Either is a great choice, particularly for beginners. If you're willing to spend $50 more, however, the Fitbit Charge 2 is our Editors' Choice. It has an informative display, continuous heart rate monitoring, guided breathing exercises, and interval training, which is certainly worth the jump in price for more serious athletes.

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Timothy Torres is a Junior Analyst on PCMag's consumer electronics team. He covers wearables, digital home, and various cool gadgets including the occasional video game. He has written all manner of copy for Computer Shopper, The Jersey Journal, Radio One, Random House, and 2D-X. Before entering the tech world, he attended New York University and worked in education as an art instructor. In his spare time he dabbles in theater, sketches comics, eats a lot of sushi and watches too many movies. Twitter: @pleasedtomeetyaMore »